How should I create a realistic landscape based on a real place?
This is a quite long task to do. 

First you'll also need some texturing for the ground. 

Then you'll need to have the models of all the building, then texture every one of them. Then the same thing for the roads and so on...

Their is an addon call blenderGiS (https://github.com/domlysz/BlenderGIS) which can take care of importing google data, i.e. building (the one google knows the shape) and road (it import the road a curves i believe). 

This solve partially the problem of how to get all the 3D model in blender. However, you'll have to do some modelling for the road or if you want very realistic building model since google has only the very low poly models of building. 

Then you need to texture everything.... So good luck !